On Tue, Jul 16, 2013 at 4:49 PM, Juan Luis Cano <juanlu001@gmail.com> wrote:

Hello all,

I've been trying the scipy.signal module lately for some easy things and
I had an idea, but I thought it would be better to bring it up in the
mailing list before filing a PR on GitHub.

My proposal is to implement the __call__ method on signal.lti objects so
it returns the value on the transfer function.

I took the idea from the `bode` function. This line:

y = numpy.polyval(sys.num, jw) / numpy.polyval(sys.den, jw)

(https://github.com/scipy/scipy/blob/v0.12.0/scipy/signal/ltisys.py#L940)

could be moved to signal.lti.__call__, and then in `bode` write

y = sys(jw)

The detail is trivial (so is the implementation) but I think it would be
a useful thing. What do others think? Shall I open a pull request?

Not sure, is writing

y = lti_sys(jw)

instead of

jw, y = lti_sys.freqresp(jw)

clearer and umambiguous? It may make sense, but would be good to get the opinion of some users on this.

Ralf